Melanin and Cellular Reactions to Ultraviolet Radiation

THERE has been much discussion about the importance of melanin in protecting skin against the damaging effects of sunlight and/or ultraviolet radiation^1–4; absorption and scattering by melanin protect intracellular organelles and cells in vitro^5,6. But we now believe that a number of the so-called “sunburn cells”, the dyskeratotic cells present in epidermis 12–48 h after irradiation^7–9, contain granules of melanin. Furthermore, they contain more granules than neighbouring, apparently undamaged cells. Thus paradoxically, cells containing what should be a protective compound are killed, while those containing less or none are apparently undamaged.